// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. Neither the name of the copyright holders nor the names of its
//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
package org.springframework.asm;

/**
 * The constant pool entries, the BootstrapMethods attribute entries and the (ASM specific) type
 * table entries of a class.
 *
 * @author Eric Bruneton
 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.4">JVMS
 * 4.4</a>
 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.23">JVMS
 * 4.7.23</a>
 */
final class SymbolTable {

	/**
	 * The ClassWriter to which this SymbolTable belongs. This is only used to get access to {@link
	 * ClassWriter#getCommonSuperClass} and to serialize custom attributes with {@link
	 * Attribute#write}.
	 */
	final ClassWriter classWriter;

	/**
	 * The ClassReader from which this SymbolTable was constructed, or {@literal null} if it was
	 * constructed from scratch.
	 */
	private final ClassReader sourceClassReader;

	/**
	 * The major version number of the class to which this symbol table belongs.
	 */
	private int majorVersion;

	/**
	 * The internal name of the class to which this symbol table belongs.
	 */
	private String className;

	/**
	 * The total number of {@link Entry} instances in {@link #entries}. This includes entries that are
	 * accessible (recursively) via {@link Entry#next}.
	 */
	private int entryCount;

	/**
	 * A hash set of all the entries in this SymbolTable (this includes the constant pool entries, the
	 * bootstrap method entries and the type table entries). Each {@link Entry} instance is stored at
	 * the array index given by its hash code modulo the array size. If several entries must be stored
	 * at the same array index, they are linked together via their {@link Entry#next} field. The
	 * factory methods of this class make sure that this table does not contain duplicated entries.
	 */
	private Entry[] entries;

	/**
	 * The number of constant pool items in {@link #constantPool}, plus 1. The first constant pool
	 * item has index 1, and long and double items count for two items.
	 */
	private int constantPoolCount;

	/**
	 * The content of the ClassFile's constant_pool JVMS structure corresponding to this SymbolTable.
	 * The ClassFile's constant_pool_count field is <i>not</i> included.
	 */
	private ByteVector constantPool;

	/**
	 * The number of bootstrap methods in {@link #bootstrapMethods}. Corresponds to the
	 * BootstrapMethods_attribute's num_bootstrap_methods field value.
	 */
	private int bootstrapMethodCount;

	/**
	 * The content of the BootstrapMethods attribute 'bootstrap_methods' array corresponding to this
	 * SymbolTable. Note that the first 6 bytes of the BootstrapMethods_attribute, and its
	 * num_bootstrap_methods field, are <i>not</i> included.
	 */
	private ByteVector bootstrapMethods;

	/**
	 * The actual number of elements in {@link #typeTable}. These elements are stored from index 0 to
	 * typeCount (excluded). The other array entries are empty.
	 */
	private int typeCount;

	/**
	 * An ASM specific type table used to temporarily store internal names that will not necessarily
	 * be stored in the constant pool. This type table is used by the control flow and data flow
	 * analysis algorithm used to compute stack map frames from scratch. This array stores {@link
	 * Symbol#TYPE_TAG} and {@link Symbol#UNINITIALIZED_TYPE_TAG}) Symbol. The type symbol at index
	 * {@code i} has its {@link Symbol#index} equal to {@code i} (and vice versa).
	 */
	private Entry[] typeTable;

	/**
	 * Constructs a new, empty SymbolTable for the given ClassWriter.
	 *
	 * @param classWriter a ClassWriter.
	 */
	SymbolTable(final ClassWriter classWriter) {
		this.classWriter = classWriter;
		this.sourceClassReader = null;
		this.entries = new Entry[256];
		this.constantPoolCount = 1;
		this.constantPool = new ByteVector();
	}

	/**
	 * Constructs a new SymbolTable for the given ClassWriter, initialized with the constant pool and
	 * bootstrap methods of the given ClassReader.
	 *
	 * @param classWriter a ClassWriter.
	 * @param classReader the ClassReader whose constant pool and bootstrap methods must be copied to
	 *                    initialize the SymbolTable.
	 */
	SymbolTable(final ClassWriter classWriter, final ClassReader classReader) {
		this.classWriter = classWriter;
		this.sourceClassReader = classReader;

		// Copy the constant pool binary content.
		byte[] inputBytes = classReader.classFileBuffer;
		int constantPoolOffset = classReader.getItem(1) - 1;
		int constantPoolLength = classReader.header - constantPoolOffset;
		constantPoolCount = classReader.getItemCount();
		constantPool = new ByteVector(constantPoolLength);
		constantPool.putByteArray(inputBytes, constantPoolOffset, constantPoolLength);

		// Add the constant pool items in the symbol table entries. Reserve enough space in 'entries' to
		// avoid too many hash set collisions (entries is not dynamically resized by the addConstant*
		// method calls below), and to account for bootstrap method entries.
		entries = new Entry[constantPoolCount * 2];
		char[] charBuffer = new char[classReader.getMaxStringLength()];
		boolean hasBootstrapMethods = false;
		int itemIndex = 1;
		while (itemIndex < constantPoolCount) {
			int itemOffset = classReader.getItem(itemIndex);
			int itemTag = inputBytes[itemOffset - 1];
			int nameAndTypeItemOffset;
			switch (itemTag) {
				case Symbol.CONSTANT_FIELDREF_TAG:
				case Symbol.CONSTANT_METHODREF_TAG:
				case Symbol.CONSTANT_INTERFACE_METHODREF_TAG:
					nameAndTypeItemOffset =
							classReader.getItem(classReader.readUnsignedShort(itemOffset + 2));
					addConstantMemberReference(
							itemIndex,
							itemTag,
							classReader.readClass(itemOffset, charBuffer),
							classReader.readUTF8(nameAndTypeItemOffset, charBuffer),
							classReader.readUTF8(nameAndTypeItemOffset + 2, charBuffer));
					break;
				case Symbol.CONSTANT_INTEGER_TAG:
				case Symbol.CONSTANT_FLOAT_TAG:
					addConstantIntegerOrFloat(itemIndex, itemTag, classReader.readInt(itemOffset));
					break;
				case Symbol.CONSTANT_NAME_AND_TYPE_TAG:
					addConstantNameAndType(
							itemIndex,
							classReader.readUTF8(itemOffset, charBuffer),
							classReader.readUTF8(itemOffset + 2, charBuffer));
					break;
				case Symbol.CONSTANT_LONG_TAG:
				case Symbol.CONSTANT_DOUBLE_TAG:
					addConstantLongOrDouble(itemIndex, itemTag, classReader.readLong(itemOffset));
					break;
				case Symbol.CONSTANT_UTF8_TAG:
					addConstantUtf8(itemIndex, classReader.readUtf(itemIndex, charBuffer));
					break;
				case Symbol.CONSTANT_METHOD_HANDLE_TAG:
					int memberRefItemOffset =
							classReader.getItem(classReader.readUnsignedShort(itemOffset + 1));
					nameAndTypeItemOffset =
							classReader.getItem(classReader.readUnsignedShort(memberRefItemOffset + 2));
					addConstantMethodHandle(
							itemIndex,
							classReader.readByte(itemOffset),
							classReader.readClass(memberRefItemOffset, charBuffer),
							classReader.readUTF8(nameAndTypeItemOffset, charBuffer),
							classReader.readUTF8(nameAndTypeItemOffset + 2, charBuffer));
					break;
				case Symbol.CONSTANT_DYNAMIC_TAG:
				case Symbol.CONSTANT_INVOKE_DYNAMIC_TAG:
					hasBootstrapMethods = true;
					nameAndTypeItemOffset =
							classReader.getItem(classReader.readUnsignedShort(itemOffset + 2));
					addConstantDynamicOrInvokeDynamicReference(
							itemTag,
							itemIndex,
							classReader.readUTF8(nameAndTypeItemOffset, charBuffer),
							classReader.readUTF8(nameAndTypeItemOffset + 2, charBuffer),
							classReader.readUnsignedShort(itemOffset));
					break;
				case Symbol.CONSTANT_STRING_TAG:
				case Symbol.CONSTANT_CLASS_TAG:
				case Symbol.CONSTANT_METHOD_TYPE_TAG:
				case Symbol.CONSTANT_MODULE_TAG:
				case Symbol.CONSTANT_PACKAGE_TAG:
					addConstantUtf8Reference(
							itemIndex, itemTag, classReader.readUTF8(itemOffset, charBuffer));
					break;
				default:
					throw new IllegalArgumentException();
			}
			itemIndex +=
					(itemTag == Symbol.CONSTANT_LONG_TAG || itemTag == Symbol.CONSTANT_DOUBLE_TAG) ? 2 : 1;
		}

		// Copy the BootstrapMethods, if any.
		if (hasBootstrapMethods) {
			copyBootstrapMethods(classReader, charBuffer);
		}
	}

	/**
	 * Read the BootstrapMethods 'bootstrap_methods' array binary content and add them as entries of
	 * the SymbolTable.
	 *
	 * @param classReader the ClassReader whose bootstrap methods must be copied to initialize the
	 *                    SymbolTable.
	 * @param charBuffer  a buffer used to read strings in the constant pool.
	 */
	private void copyBootstrapMethods(final ClassReader classReader, final char[] charBuffer) {
		// Find attributOffset of the 'bootstrap_methods' array.
		byte[] inputBytes = classReader.classFileBuffer;
		int currentAttributeOffset = classReader.getFirstAttributeOffset();
		for (int i = classReader.readUnsignedShort(currentAttributeOffset - 2); i > 0; --i) {
			String attributeName = classReader.readUTF8(currentAttributeOffset, charBuffer);
			if (Constants.BOOTSTRAP_METHODS.equals(attributeName)) {
				bootstrapMethodCount = classReader.readUnsignedShort(currentAttributeOffset + 6);
				break;
			}
			currentAttributeOffset += 6 + classReader.readInt(currentAttributeOffset + 2);
		}
		if (bootstrapMethodCount > 0) {
			// Compute the offset and the length of the BootstrapMethods 'bootstrap_methods' array.
			int bootstrapMethodsOffset = currentAttributeOffset + 8;
			int bootstrapMethodsLength = classReader.readInt(currentAttributeOffset + 2) - 2;
			bootstrapMethods = new ByteVector(bootstrapMethodsLength);
			bootstrapMethods.putByteArray(inputBytes, bootstrapMethodsOffset, bootstrapMethodsLength);

			// Add each bootstrap method in the symbol table entries.
			int currentOffset = bootstrapMethodsOffset;
			for (int i = 0; i < bootstrapMethodCount; i++) {
				int offset = currentOffset - bootstrapMethodsOffset;
				int bootstrapMethodRef = classReader.readUnsignedShort(currentOffset);
				currentOffset += 2;
				int numBootstrapArguments = classReader.readUnsignedShort(currentOffset);
				currentOffset += 2;
				int hashCode = classReader.readConst(bootstrapMethodRef, charBuffer).hashCode();
				while (numBootstrapArguments-- > 0) {
					int bootstrapArgument = classReader.readUnsignedShort(currentOffset);
					currentOffset += 2;
					hashCode ^= classReader.readConst(bootstrapArgument, charBuffer).hashCode();
				}
				add(new Entry(i, Symbol.BOOTSTRAP_METHOD_TAG, offset, hashCode & 0x7FFFFFFF));
			}
		}
	}

	/**
	 * Returns the ClassReader from which this SymbolTable was constructed.
	 *
	 * @return the ClassReader from which this SymbolTable was constructed, or {@literal null} if it
	 * was constructed from scratch.
	 */
	ClassReader getSource() {
		return sourceClassReader;
	}

	/**
	 * Returns the major version of the class to which this symbol table belongs.
	 *
	 * @return the major version of the class to which this symbol table belongs.
	 */
	int getMajorVersion() {
		return majorVersion;
	}

	/**
	 * Returns the internal name of the class to which this symbol table belongs.
	 *
	 * @return the internal name of the class to which this symbol table belongs.
	 */
	String getClassName() {
		return className;
	}

	/**
	 * Sets the major version and the name of the class to which this symbol table belongs. Also adds
	 * the class name to the constant pool.
	 *
	 * @param majorVersion a major ClassFile version number.
	 * @param className    an internal class name.
	 * @return the constant pool index of a new or already existing Symbol with the given class name.
	 */
	int setMajorVersionAndClassName(final int majorVersion, final String className) {
		this.majorVersion = majorVersion;
		this.className = className;
		return addConstantClass(className).index;
	}

	/**
	 * Returns the number of items in this symbol table's constant_pool array (plus 1).
	 *
	 * @return the number of items in this symbol table's constant_pool array (plus 1).
	 */
	int getConstantPoolCount() {
		return constantPoolCount;
	}

	/**
	 * Returns the length in bytes of this symbol table's constant_pool array.
	 *
	 * @return the length in bytes of this symbol table's constant_pool array.
	 */
	int getConstantPoolLength() {
		return constantPool.length;
	}

	/**
	 * Puts this symbol table's constant_pool array in the given ByteVector, preceded by the
	 * constant_pool_count value.
	 *
	 * @param output where the JVMS ClassFile's constant_pool array must be put.
	 */
	void putConstantPool(final ByteVector output) {
		output.putShort(constantPoolCount).putByteArray(constantPool.data, 0, constantPool.length);
	}

	/**
	 * Returns the size in bytes of this symbol table's BootstrapMethods attribute. Also adds the
	 * attribute name in the constant pool.
	 *
	 * @return the size in bytes of this symbol table's BootstrapMethods attribute.
	 */
	int computeBootstrapMethodsSize() {
		if (bootstrapMethods != null) {
			addConstantUtf8(Constants.BOOTSTRAP_METHODS);
			return 8 + bootstrapMethods.length;
		} else {
			return 0;
		}
	}

	/**
	 * Puts this symbol table's BootstrapMethods attribute in the given ByteVector. This includes the
	 * 6 attribute header bytes and the num_bootstrap_methods value.
	 *
	 * @param output where the JVMS BootstrapMethods attribute must be put.
	 */
	void putBootstrapMethods(final ByteVector output) {
		if (bootstrapMethods != null) {
			output
					.putShort(addConstantUtf8(Constants.BOOTSTRAP_METHODS))
					.putInt(bootstrapMethods.length + 2)
					.putShort(bootstrapMethodCount)
					.putByteArray(bootstrapMethods.data, 0, bootstrapMethods.length);
		}
	}

	// -----------------------------------------------------------------------------------------------
	// Generic symbol table entries management.
	// -----------------------------------------------------------------------------------------------

	/**
	 * Returns the list of entries which can potentially have the given hash code.
	 *
	 * @param hashCode a {@link Entry#hashCode} value.
	 * @return the list of entries which can potentially have the given hash code. The list is stored
	 * via the {@link Entry#next} field.
	 */
	private Entry get(final int hashCode) {
		return entries[hashCode % entries.length];
	}

	/**
	 * Puts the given entry in the {@link #entries} hash set. This method does <i>not</i> check
	 * whether {@link #entries} already contains a similar entry or not. {@link #entries} is resized
	 * if necessary to avoid hash collisions (multiple entries needing to be stored at the same {@link
	 * #entries} array index) as much as possible, with reasonable memory usage.
	 *
	 * @param entry an Entry (which must not already be contained in {@link #entries}).
	 * @return the given entry
	 */
	private Entry put(final Entry entry) {
		if (entryCount > (entries.length * 3) / 4) {
			int currentCapacity = entries.length;
			int newCapacity = currentCapacity * 2 + 1;
			Entry[] newEntries = new Entry[newCapacity];
			for (int i = currentCapacity - 1; i >= 0; --i) {
				Entry currentEntry = entries[i];
				while (currentEntry != null) {
					int newCurrentEntryIndex = currentEntry.hashCode % newCapacity;
					Entry nextEntry = currentEntry.next;
					currentEntry.next = newEntries[newCurrentEntryIndex];
					newEntries[newCurrentEntryIndex] = currentEntry;
					currentEntry = nextEntry;
				}
			}
			entries = newEntries;
		}
		entryCount++;
		int index = entry.hashCode % entries.length;
		entry.next = entries[index];
		return entries[index] = entry;
	}

	/**
	 * Adds the given entry in the {@link #entries} hash set. This method does <i>not</i> check
	 * whether {@link #entries} already contains a similar entry or not, and does <i>not</i> resize
	 * {@link #entries} if necessary.
	 *
	 * @param entry an Entry (which must not already be contained in {@link #entries}).
	 */
	private void add(final Entry entry) {
		entryCount++;
		int index = entry.hashCode % entries.length;
		entry.next = entries[index];
		entries[index] = entry;
	}

	// -----------------------------------------------------------------------------------------------
	// Constant pool entries management.
	// -----------------------------------------------------------------------------------------------

	/**
	 * Adds a number or string constant to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param value the value of the constant to be added to the constant pool. This parameter must be
	 *              an {@link Integer}, {@link Byte}, {@link Character}, {@link Short}, {@link Boolean}, {@link
	 *              Float}, {@link Long}, {@link Double}, {@link String}, {@link Type} or {@link Handle}.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstant(final Object value) {
		if (value instanceof Integer) {
			return addConstantInteger(((Integer) value).intValue());
		} else if (value instanceof Byte) {
			return addConstantInteger(((Byte) value).intValue());
		} else if (value instanceof Character) {
			return addConstantInteger(((Character) value).charValue());
		} else if (value instanceof Short) {
			return addConstantInteger(((Short) value).intValue());
		} else if (value instanceof Boolean) {
			return addConstantInteger(((Boolean) value).booleanValue() ? 1 : 0);
		} else if (value instanceof Float) {
			return addConstantFloat(((Float) value).floatValue());
		} else if (value instanceof Long) {
			return addConstantLong(((Long) value).longValue());
		} else if (value instanceof Double) {
			return addConstantDouble(((Double) value).doubleValue());
		} else if (value instanceof String) {
			return addConstantString((String) value);
		} else if (value instanceof Type) {
			Type type = (Type) value;
			int typeSort = type.getSort();
			if (typeSort == Type.OBJECT) {
				return addConstantClass(type.getInternalName());
			} else if (typeSort == Type.METHOD) {
				return addConstantMethodType(type.getDescriptor());
			} else { // type is a primitive or array type.
				return addConstantClass(type.getDescriptor());
			}
		} else if (value instanceof Handle) {
			Handle handle = (Handle) value;
			return addConstantMethodHandle(
					handle.getTag(),
					handle.getOwner(),
					handle.getName(),
					handle.getDesc(),
					handle.isInterface());
		} else if (value instanceof ConstantDynamic) {
			ConstantDynamic constantDynamic = (ConstantDynamic) value;
			return addConstantDynamic(
					constantDynamic.getName(),
					constantDynamic.getDescriptor(),
					constantDynamic.getBootstrapMethod(),
					constantDynamic.getBootstrapMethodArgumentsUnsafe());
		} else {
			throw new IllegalArgumentException("value " + value);
		}
	}

	/**
	 * Adds a CONSTANT_Class_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param value the internal name of a class.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantClass(final String value) {
		return addConstantUtf8Reference(Symbol.CONSTANT_CLASS_TAG, value);
	}

	/**
	 * Adds a CONSTANT_Fieldref_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param owner      the internal name of a class.
	 * @param name       a field name.
	 * @param descriptor a field descriptor.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantFieldref(final String owner, final String name, final String descriptor) {
		return addConstantMemberReference(Symbol.CONSTANT_FIELDREF_TAG, owner, name, descriptor);
	}

	/**
	 * Adds a CONSTANT_Methodref_info or CONSTANT_InterfaceMethodref_info to the constant pool of this
	 * symbol table. Does nothing if the constant pool already contains a similar item.
	 *
	 * @param owner       the internal name of a class.
	 * @param name        a method name.
	 * @param descriptor  a method descriptor.
	 * @param isInterface whether owner is an interface or not.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantMethodref(
			final String owner, final String name, final String descriptor, final boolean isInterface) {
		int tag = isInterface ? Symbol.CONSTANT_INTERFACE_METHODREF_TAG : Symbol.CONSTANT_METHODREF_TAG;
		return addConstantMemberReference(tag, owner, name, descriptor);
	}

	/**
	 * Adds a CONSTANT_Fieldref_info, CONSTANT_Methodref_info or CONSTANT_InterfaceMethodref_info to
	 * the constant pool of this symbol table. Does nothing if the constant pool already contains a
	 * similar item.
	 *
	 * @param tag        one of {@link Symbol#CONSTANT_FIELDREF_TAG}, {@link Symbol#CONSTANT_METHODREF_TAG}
	 *                   or {@link Symbol#CONSTANT_INTERFACE_METHODREF_TAG}.
	 * @param owner      the internal name of a class.
	 * @param name       a field or method name.
	 * @param descriptor a field or method descriptor.
	 * @return a new or already existing Symbol with the given value.
	 */
	private Entry addConstantMemberReference(
			final int tag, final String owner, final String name, final String descriptor) {
		int hashCode = hash(tag, owner, name, descriptor);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == tag
					&& entry.hashCode == hashCode
					&& entry.owner.equals(owner)
					&& entry.name.equals(name)
					&& entry.value.equals(descriptor)) {
				return entry;
			}
			entry = entry.next;
		}
		constantPool.put122(
				tag, addConstantClass(owner).index, addConstantNameAndType(name, descriptor));
		return put(new Entry(constantPoolCount++, tag, owner, name, descriptor, 0, hashCode));
	}

	/**
	 * Adds a new CONSTANT_Fieldref_info, CONSTANT_Methodref_info or CONSTANT_InterfaceMethodref_info
	 * to the constant pool of this symbol table.
	 *
	 * @param index      the constant pool index of the new Symbol.
	 * @param tag        one of {@link Symbol#CONSTANT_FIELDREF_TAG}, {@link Symbol#CONSTANT_METHODREF_TAG}
	 *                   or {@link Symbol#CONSTANT_INTERFACE_METHODREF_TAG}.
	 * @param owner      the internal name of a class.
	 * @param name       a field or method name.
	 * @param descriptor a field or method descriptor.
	 */
	private void addConstantMemberReference(
			final int index,
			final int tag,
			final String owner,
			final String name,
			final String descriptor) {
		add(new Entry(index, tag, owner, name, descriptor, 0, hash(tag, owner, name, descriptor)));
	}

	/**
	 * Adds a CONSTANT_String_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param value a string.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantString(final String value) {
		return addConstantUtf8Reference(Symbol.CONSTANT_STRING_TAG, value);
	}

	/**
	 * Adds a CONSTANT_Integer_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param value an int.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantInteger(final int value) {
		return addConstantIntegerOrFloat(Symbol.CONSTANT_INTEGER_TAG, value);
	}

	/**
	 * Adds a CONSTANT_Float_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param value a float.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantFloat(final float value) {
		return addConstantIntegerOrFloat(Symbol.CONSTANT_FLOAT_TAG, Float.floatToRawIntBits(value));
	}

	/**
	 * Adds a CONSTANT_Integer_info or CONSTANT_Float_info to the constant pool of this symbol table.
	 * Does nothing if the constant pool already contains a similar item.
	 *
	 * @param tag   one of {@link Symbol#CONSTANT_INTEGER_TAG} or {@link Symbol#CONSTANT_FLOAT_TAG}.
	 * @param value an int or float.
	 * @return a constant pool constant with the given tag and primitive values.
	 */
	private Symbol addConstantIntegerOrFloat(final int tag, final int value) {
		int hashCode = hash(tag, value);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == tag && entry.hashCode == hashCode && entry.data == value) {
				return entry;
			}
			entry = entry.next;
		}
		constantPool.putByte(tag).putInt(value);
		return put(new Entry(constantPoolCount++, tag, value, hashCode));
	}

	/**
	 * Adds a new CONSTANT_Integer_info or CONSTANT_Float_info to the constant pool of this symbol
	 * table.
	 *
	 * @param index the constant pool index of the new Symbol.
	 * @param tag   one of {@link Symbol#CONSTANT_INTEGER_TAG} or {@link Symbol#CONSTANT_FLOAT_TAG}.
	 * @param value an int or float.
	 */
	private void addConstantIntegerOrFloat(final int index, final int tag, final int value) {
		add(new Entry(index, tag, value, hash(tag, value)));
	}

	/**
	 * Adds a CONSTANT_Long_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param value a long.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantLong(final long value) {
		return addConstantLongOrDouble(Symbol.CONSTANT_LONG_TAG, value);
	}

	/**
	 * Adds a CONSTANT_Double_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param value a double.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantDouble(final double value) {
		return addConstantLongOrDouble(Symbol.CONSTANT_DOUBLE_TAG, Double.doubleToRawLongBits(value));
	}

	/**
	 * Adds a CONSTANT_Long_info or CONSTANT_Double_info to the constant pool of this symbol table.
	 * Does nothing if the constant pool already contains a similar item.
	 *
	 * @param tag   one of {@link Symbol#CONSTANT_LONG_TAG} or {@link Symbol#CONSTANT_DOUBLE_TAG}.
	 * @param value a long or double.
	 * @return a constant pool constant with the given tag and primitive values.
	 */
	private Symbol addConstantLongOrDouble(final int tag, final long value) {
		int hashCode = hash(tag, value);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == tag && entry.hashCode == hashCode && entry.data == value) {
				return entry;
			}
			entry = entry.next;
		}
		int index = constantPoolCount;
		constantPool.putByte(tag).putLong(value);
		constantPoolCount += 2;
		return put(new Entry(index, tag, value, hashCode));
	}

	/**
	 * Adds a new CONSTANT_Long_info or CONSTANT_Double_info to the constant pool of this symbol
	 * table.
	 *
	 * @param index the constant pool index of the new Symbol.
	 * @param tag   one of {@link Symbol#CONSTANT_LONG_TAG} or {@link Symbol#CONSTANT_DOUBLE_TAG}.
	 * @param value a long or double.
	 */
	private void addConstantLongOrDouble(final int index, final int tag, final long value) {
		add(new Entry(index, tag, value, hash(tag, value)));
	}

	/**
	 * Adds a CONSTANT_NameAndType_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param name       a field or method name.
	 * @param descriptor a field or method descriptor.
	 * @return a new or already existing Symbol with the given value.
	 */
	int addConstantNameAndType(final String name, final String descriptor) {
		final int tag = Symbol.CONSTANT_NAME_AND_TYPE_TAG;
		int hashCode = hash(tag, name, descriptor);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == tag
					&& entry.hashCode == hashCode
					&& entry.name.equals(name)
					&& entry.value.equals(descriptor)) {
				return entry.index;
			}
			entry = entry.next;
		}
		constantPool.put122(tag, addConstantUtf8(name), addConstantUtf8(descriptor));
		return put(new Entry(constantPoolCount++, tag, name, descriptor, hashCode)).index;
	}

	/**
	 * Adds a new CONSTANT_NameAndType_info to the constant pool of this symbol table.
	 *
	 * @param index      the constant pool index of the new Symbol.
	 * @param name       a field or method name.
	 * @param descriptor a field or method descriptor.
	 */
	private void addConstantNameAndType(final int index, final String name, final String descriptor) {
		final int tag = Symbol.CONSTANT_NAME_AND_TYPE_TAG;
		add(new Entry(index, tag, name, descriptor, hash(tag, name, descriptor)));
	}

	/**
	 * Adds a CONSTANT_Utf8_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param value a string.
	 * @return a new or already existing Symbol with the given value.
	 */
	int addConstantUtf8(final String value) {
		int hashCode = hash(Symbol.CONSTANT_UTF8_TAG, value);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == Symbol.CONSTANT_UTF8_TAG
					&& entry.hashCode == hashCode
					&& entry.value.equals(value)) {
				return entry.index;
			}
			entry = entry.next;
		}
		constantPool.putByte(Symbol.CONSTANT_UTF8_TAG).putUTF8(value);
		return put(new Entry(constantPoolCount++, Symbol.CONSTANT_UTF8_TAG, value, hashCode)).index;
	}

	/**
	 * Adds a new CONSTANT_String_info to the constant pool of this symbol table.
	 *
	 * @param index the constant pool index of the new Symbol.
	 * @param value a string.
	 */
	private void addConstantUtf8(final int index, final String value) {
		add(new Entry(index, Symbol.CONSTANT_UTF8_TAG, value, hash(Symbol.CONSTANT_UTF8_TAG, value)));
	}

	/**
	 * Adds a CONSTANT_MethodHandle_info to the constant pool of this symbol table. Does nothing if
	 * the constant pool already contains a similar item.
	 *
	 * @param referenceKind one of {@link Opcodes#H_GETFIELD}, {@link Opcodes#H_GETSTATIC}, {@link
	 *                      Opcodes#H_PUTFIELD}, {@link Opcodes#H_PUTSTATIC}, {@link Opcodes#H_INVOKEVIRTUAL}, {@link
	 *                      Opcodes#H_INVOKESTATIC}, {@link Opcodes#H_INVOKESPECIAL}, {@link
	 *                      Opcodes#H_NEWINVOKESPECIAL} or {@link Opcodes#H_INVOKEINTERFACE}.
	 * @param owner         the internal name of a class of interface.
	 * @param name          a field or method name.
	 * @param descriptor    a field or method descriptor.
	 * @param isInterface   whether owner is an interface or not.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantMethodHandle(
			final int referenceKind,
			final String owner,
			final String name,
			final String descriptor,
			final boolean isInterface) {
		final int tag = Symbol.CONSTANT_METHOD_HANDLE_TAG;
		// Note that we don't need to include isInterface in the hash computation, because it is
		// redundant with owner (we can't have the same owner with different isInterface values).
		int hashCode = hash(tag, owner, name, descriptor, referenceKind);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == tag
					&& entry.hashCode == hashCode
					&& entry.data == referenceKind
					&& entry.owner.equals(owner)
					&& entry.name.equals(name)
					&& entry.value.equals(descriptor)) {
				return entry;
			}
			entry = entry.next;
		}
		if (referenceKind <= Opcodes.H_PUTSTATIC) {
			constantPool.put112(tag, referenceKind, addConstantFieldref(owner, name, descriptor).index);
		} else {
			constantPool.put112(
					tag, referenceKind, addConstantMethodref(owner, name, descriptor, isInterface).index);
		}
		return put(
				new Entry(constantPoolCount++, tag, owner, name, descriptor, referenceKind, hashCode));
	}

	/**
	 * Adds a new CONSTANT_MethodHandle_info to the constant pool of this symbol table.
	 *
	 * @param index         the constant pool index of the new Symbol.
	 * @param referenceKind one of {@link Opcodes#H_GETFIELD}, {@link Opcodes#H_GETSTATIC}, {@link
	 *                      Opcodes#H_PUTFIELD}, {@link Opcodes#H_PUTSTATIC}, {@link Opcodes#H_INVOKEVIRTUAL}, {@link
	 *                      Opcodes#H_INVOKESTATIC}, {@link Opcodes#H_INVOKESPECIAL}, {@link
	 *                      Opcodes#H_NEWINVOKESPECIAL} or {@link Opcodes#H_INVOKEINTERFACE}.
	 * @param owner         the internal name of a class of interface.
	 * @param name          a field or method name.
	 * @param descriptor    a field or method descriptor.
	 */
	private void addConstantMethodHandle(
			final int index,
			final int referenceKind,
			final String owner,
			final String name,
			final String descriptor) {
		final int tag = Symbol.CONSTANT_METHOD_HANDLE_TAG;
		int hashCode = hash(tag, owner, name, descriptor, referenceKind);
		add(new Entry(index, tag, owner, name, descriptor, referenceKind, hashCode));
	}

	/**
	 * Adds a CONSTANT_MethodType_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param methodDescriptor a method descriptor.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantMethodType(final String methodDescriptor) {
		return addConstantUtf8Reference(Symbol.CONSTANT_METHOD_TYPE_TAG, methodDescriptor);
	}

	/**
	 * Adds a CONSTANT_Dynamic_info to the constant pool of this symbol table. Also adds the related
	 * bootstrap method to the BootstrapMethods of this symbol table. Does nothing if the constant
	 * pool already contains a similar item.
	 *
	 * @param name                     a method name.
	 * @param descriptor               a field descriptor.
	 * @param bootstrapMethodHandle    a bootstrap method handle.
	 * @param bootstrapMethodArguments the bootstrap method arguments.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantDynamic(
			final String name,
			final String descriptor,
			final Handle bootstrapMethodHandle,
			final Object... bootstrapMethodArguments) {
		Symbol bootstrapMethod = addBootstrapMethod(bootstrapMethodHandle, bootstrapMethodArguments);
		return addConstantDynamicOrInvokeDynamicReference(
				Symbol.CONSTANT_DYNAMIC_TAG, name, descriptor, bootstrapMethod.index);
	}

	/**
	 * Adds a CONSTANT_InvokeDynamic_info to the constant pool of this symbol table. Also adds the
	 * related bootstrap method to the BootstrapMethods of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param name                     a method name.
	 * @param descriptor               a method descriptor.
	 * @param bootstrapMethodHandle    a bootstrap method handle.
	 * @param bootstrapMethodArguments the bootstrap method arguments.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantInvokeDynamic(
			final String name,
			final String descriptor,
			final Handle bootstrapMethodHandle,
			final Object... bootstrapMethodArguments) {
		Symbol bootstrapMethod = addBootstrapMethod(bootstrapMethodHandle, bootstrapMethodArguments);
		return addConstantDynamicOrInvokeDynamicReference(
				Symbol.CONSTANT_INVOKE_DYNAMIC_TAG, name, descriptor, bootstrapMethod.index);
	}

	/**
	 * Adds a CONSTANT_Dynamic or a CONSTANT_InvokeDynamic_info to the constant pool of this symbol
	 * table. Does nothing if the constant pool already contains a similar item.
	 *
	 * @param tag                  one of {@link Symbol#CONSTANT_DYNAMIC_TAG} or {@link
	 *                             Symbol#CONSTANT_INVOKE_DYNAMIC_TAG}.
	 * @param name                 a method name.
	 * @param descriptor           a field descriptor for CONSTANT_DYNAMIC_TAG) or a method descriptor for
	 *                             CONSTANT_INVOKE_DYNAMIC_TAG.
	 * @param bootstrapMethodIndex the index of a bootstrap method in the BootstrapMethods attribute.
	 * @return a new or already existing Symbol with the given value.
	 */
	private Symbol addConstantDynamicOrInvokeDynamicReference(
			final int tag, final String name, final String descriptor, final int bootstrapMethodIndex) {
		int hashCode = hash(tag, name, descriptor, bootstrapMethodIndex);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == tag
					&& entry.hashCode == hashCode
					&& entry.data == bootstrapMethodIndex
					&& entry.name.equals(name)
					&& entry.value.equals(descriptor)) {
				return entry;
			}
			entry = entry.next;
		}
		constantPool.put122(tag, bootstrapMethodIndex, addConstantNameAndType(name, descriptor));
		return put(
				new Entry(
						constantPoolCount++, tag, null, name, descriptor, bootstrapMethodIndex, hashCode));
	}

	/**
	 * Adds a new CONSTANT_Dynamic_info or CONSTANT_InvokeDynamic_info to the constant pool of this
	 * symbol table.
	 *
	 * @param tag                  one of {@link Symbol#CONSTANT_DYNAMIC_TAG} or {@link
	 *                             Symbol#CONSTANT_INVOKE_DYNAMIC_TAG}.
	 * @param index                the constant pool index of the new Symbol.
	 * @param name                 a method name.
	 * @param descriptor           a field descriptor for CONSTANT_DYNAMIC_TAG or a method descriptor for
	 *                             CONSTANT_INVOKE_DYNAMIC_TAG.
	 * @param bootstrapMethodIndex the index of a bootstrap method in the BootstrapMethods attribute.
	 */
	private void addConstantDynamicOrInvokeDynamicReference(
			final int tag,
			final int index,
			final String name,
			final String descriptor,
			final int bootstrapMethodIndex) {
		int hashCode = hash(tag, name, descriptor, bootstrapMethodIndex);
		add(new Entry(index, tag, null, name, descriptor, bootstrapMethodIndex, hashCode));
	}

	/**
	 * Adds a CONSTANT_Module_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param moduleName a fully qualified name (using dots) of a module.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantModule(final String moduleName) {
		return addConstantUtf8Reference(Symbol.CONSTANT_MODULE_TAG, moduleName);
	}

	/**
	 * Adds a CONSTANT_Package_info to the constant pool of this symbol table. Does nothing if the
	 * constant pool already contains a similar item.
	 *
	 * @param packageName the internal name of a package.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addConstantPackage(final String packageName) {
		return addConstantUtf8Reference(Symbol.CONSTANT_PACKAGE_TAG, packageName);
	}

	/**
	 * Adds a CONSTANT_Class_info, CONSTANT_String_info, CONSTANT_MethodType_info,
	 * CONSTANT_Module_info or CONSTANT_Package_info to the constant pool of this symbol table. Does
	 * nothing if the constant pool already contains a similar item.
	 *
	 * @param tag   one of {@link Symbol#CONSTANT_CLASS_TAG}, {@link Symbol#CONSTANT_STRING_TAG}, {@link
	 *              Symbol#CONSTANT_METHOD_TYPE_TAG}, {@link Symbol#CONSTANT_MODULE_TAG} or {@link
	 *              Symbol#CONSTANT_PACKAGE_TAG}.
	 * @param value an internal class name, an arbitrary string, a method descriptor, a module or a
	 *              package name, depending on tag.
	 * @return a new or already existing Symbol with the given value.
	 */
	private Symbol addConstantUtf8Reference(final int tag, final String value) {
		int hashCode = hash(tag, value);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == tag && entry.hashCode == hashCode && entry.value.equals(value)) {
				return entry;
			}
			entry = entry.next;
		}
		constantPool.put12(tag, addConstantUtf8(value));
		return put(new Entry(constantPoolCount++, tag, value, hashCode));
	}

	/**
	 * Adds a new CONSTANT_Class_info, CONSTANT_String_info, CONSTANT_MethodType_info,
	 * CONSTANT_Module_info or CONSTANT_Package_info to the constant pool of this symbol table.
	 *
	 * @param index the constant pool index of the new Symbol.
	 * @param tag   one of {@link Symbol#CONSTANT_CLASS_TAG}, {@link Symbol#CONSTANT_STRING_TAG}, {@link
	 *              Symbol#CONSTANT_METHOD_TYPE_TAG}, {@link Symbol#CONSTANT_MODULE_TAG} or {@link
	 *              Symbol#CONSTANT_PACKAGE_TAG}.
	 * @param value an internal class name, an arbitrary string, a method descriptor, a module or a
	 *              package name, depending on tag.
	 */
	private void addConstantUtf8Reference(final int index, final int tag, final String value) {
		add(new Entry(index, tag, value, hash(tag, value)));
	}

	// -----------------------------------------------------------------------------------------------
	// Bootstrap method entries management.
	// -----------------------------------------------------------------------------------------------

	/**
	 * Adds a bootstrap method to the BootstrapMethods attribute of this symbol table. Does nothing if
	 * the BootstrapMethods already contains a similar bootstrap method.
	 *
	 * @param bootstrapMethodHandle    a bootstrap method handle.
	 * @param bootstrapMethodArguments the bootstrap method arguments.
	 * @return a new or already existing Symbol with the given value.
	 */
	Symbol addBootstrapMethod(
			final Handle bootstrapMethodHandle, final Object... bootstrapMethodArguments) {
		ByteVector bootstrapMethodsAttribute = bootstrapMethods;
		if (bootstrapMethodsAttribute == null) {
			bootstrapMethodsAttribute = bootstrapMethods = new ByteVector();
		}

		// The bootstrap method arguments can be Constant_Dynamic values, which reference other
		// bootstrap methods. We must therefore add the bootstrap method arguments to the constant pool
		// and BootstrapMethods attribute first, so that the BootstrapMethods attribute is not modified
		// while adding the given bootstrap method to it, in the rest of this method.
		int numBootstrapArguments = bootstrapMethodArguments.length;
		int[] bootstrapMethodArgumentIndexes = new int[numBootstrapArguments];
		for (int i = 0; i < numBootstrapArguments; i++) {
			bootstrapMethodArgumentIndexes[i] = addConstant(bootstrapMethodArguments[i]).index;
		}

		// Write the bootstrap method in the BootstrapMethods table. This is necessary to be able to
		// compare it with existing ones, and will be reverted below if there is already a similar
		// bootstrap method.
		int bootstrapMethodOffset = bootstrapMethodsAttribute.length;
		bootstrapMethodsAttribute.putShort(
				addConstantMethodHandle(
						bootstrapMethodHandle.getTag(),
						bootstrapMethodHandle.getOwner(),
						bootstrapMethodHandle.getName(),
						bootstrapMethodHandle.getDesc(),
						bootstrapMethodHandle.isInterface())
						.index);

		bootstrapMethodsAttribute.putShort(numBootstrapArguments);
		for (int i = 0; i < numBootstrapArguments; i++) {
			bootstrapMethodsAttribute.putShort(bootstrapMethodArgumentIndexes[i]);
		}

		// Compute the length and the hash code of the bootstrap method.
		int bootstrapMethodlength = bootstrapMethodsAttribute.length - bootstrapMethodOffset;
		int hashCode = bootstrapMethodHandle.hashCode();
		for (Object bootstrapMethodArgument : bootstrapMethodArguments) {
			hashCode ^= bootstrapMethodArgument.hashCode();
		}
		hashCode &= 0x7FFFFFFF;

		// Add the bootstrap method to the symbol table or revert the above changes.
		return addBootstrapMethod(bootstrapMethodOffset, bootstrapMethodlength, hashCode);
	}

	/**
	 * Adds a bootstrap method to the BootstrapMethods attribute of this symbol table. Does nothing if
	 * the BootstrapMethods already contains a similar bootstrap method (more precisely, reverts the
	 * content of {@link #bootstrapMethods} to remove the last, duplicate bootstrap method).
	 *
	 * @param offset   the offset of the last bootstrap method in {@link #bootstrapMethods}, in bytes.
	 * @param length   the length of this bootstrap method in {@link #bootstrapMethods}, in bytes.
	 * @param hashCode the hash code of this bootstrap method.
	 * @return a new or already existing Symbol with the given value.
	 */
	private Symbol addBootstrapMethod(final int offset, final int length, final int hashCode) {
		final byte[] bootstrapMethodsData = bootstrapMethods.data;
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == Symbol.BOOTSTRAP_METHOD_TAG && entry.hashCode == hashCode) {
				int otherOffset = (int) entry.data;
				boolean isSameBootstrapMethod = true;
				for (int i = 0; i < length; ++i) {
					if (bootstrapMethodsData[offset + i] != bootstrapMethodsData[otherOffset + i]) {
						isSameBootstrapMethod = false;
						break;
					}
				}
				if (isSameBootstrapMethod) {
					bootstrapMethods.length = offset; // Revert to old position.
					return entry;
				}
			}
			entry = entry.next;
		}
		return put(new Entry(bootstrapMethodCount++, Symbol.BOOTSTRAP_METHOD_TAG, offset, hashCode));
	}

	// -----------------------------------------------------------------------------------------------
	// Type table entries management.
	// -----------------------------------------------------------------------------------------------

	/**
	 * Returns the type table element whose index is given.
	 *
	 * @param typeIndex a type table index.
	 * @return the type table element whose index is given.
	 */
	Symbol getType(final int typeIndex) {
		return typeTable[typeIndex];
	}

	/**
	 * Adds a type in the type table of this symbol table. Does nothing if the type table already
	 * contains a similar type.
	 *
	 * @param value an internal class name.
	 * @return the index of a new or already existing type Symbol with the given value.
	 */
	int addType(final String value) {
		int hashCode = hash(Symbol.TYPE_TAG, value);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == Symbol.TYPE_TAG && entry.hashCode == hashCode && entry.value.equals(value)) {
				return entry.index;
			}
			entry = entry.next;
		}
		return addTypeInternal(new Entry(typeCount, Symbol.TYPE_TAG, value, hashCode));
	}

	/**
	 * Adds an {@link Frame#ITEM_UNINITIALIZED} type in the type table of this symbol table. Does
	 * nothing if the type table already contains a similar type.
	 *
	 * @param value          an internal class name.
	 * @param bytecodeOffset the bytecode offset of the NEW instruction that created this {@link
	 *                       Frame#ITEM_UNINITIALIZED} type value.
	 * @return the index of a new or already existing type Symbol with the given value.
	 */
	int addUninitializedType(final String value, final int bytecodeOffset) {
		int hashCode = hash(Symbol.UNINITIALIZED_TYPE_TAG, value, bytecodeOffset);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == Symbol.UNINITIALIZED_TYPE_TAG
					&& entry.hashCode == hashCode
					&& entry.data == bytecodeOffset
					&& entry.value.equals(value)) {
				return entry.index;
			}
			entry = entry.next;
		}
		return addTypeInternal(
				new Entry(typeCount, Symbol.UNINITIALIZED_TYPE_TAG, value, bytecodeOffset, hashCode));
	}

	/**
	 * Adds a merged type in the type table of this symbol table. Does nothing if the type table
	 * already contains a similar type.
	 *
	 * @param typeTableIndex1 a {@link Symbol#TYPE_TAG} type, specified by its index in the type
	 *                        table.
	 * @param typeTableIndex2 another {@link Symbol#TYPE_TAG} type, specified by its index in the type
	 *                        table.
	 * @return the index of a new or already existing {@link Symbol#TYPE_TAG} type Symbol,
	 * corresponding to the common super class of the given types.
	 */
	int addMergedType(final int typeTableIndex1, final int typeTableIndex2) {
		long data =
				typeTableIndex1 < typeTableIndex2
						? typeTableIndex1 | (((long) typeTableIndex2) << 32)
						: typeTableIndex2 | (((long) typeTableIndex1) << 32);
		int hashCode = hash(Symbol.MERGED_TYPE_TAG, typeTableIndex1 + typeTableIndex2);
		Entry entry = get(hashCode);
		while (entry != null) {
			if (entry.tag == Symbol.MERGED_TYPE_TAG && entry.hashCode == hashCode && entry.data == data) {
				return entry.info;
			}
			entry = entry.next;
		}
		String type1 = typeTable[typeTableIndex1].value;
		String type2 = typeTable[typeTableIndex2].value;
		int commonSuperTypeIndex = addType(classWriter.getCommonSuperClass(type1, type2));
		put(new Entry(typeCount, Symbol.MERGED_TYPE_TAG, data, hashCode)).info = commonSuperTypeIndex;
		return commonSuperTypeIndex;
	}

	/**
	 * Adds the given type Symbol to {@link #typeTable}.
	 *
	 * @param entry a {@link Symbol#TYPE_TAG} or {@link Symbol#UNINITIALIZED_TYPE_TAG} type symbol.
	 *              The index of this Symbol must be equal to the current value of {@link #typeCount}.
	 * @return the index in {@link #typeTable} where the given type was added, which is also equal to
	 * entry's index by hypothesis.
	 */
	private int addTypeInternal(final Entry entry) {
		if (typeTable == null) {
			typeTable = new Entry[16];
		}
		if (typeCount == typeTable.length) {
			Entry[] newTypeTable = new Entry[2 * typeTable.length];
			System.arraycopy(typeTable, 0, newTypeTable, 0, typeTable.length);
			typeTable = newTypeTable;
		}
		typeTable[typeCount++] = entry;
		return put(entry).index;
	}

	// -----------------------------------------------------------------------------------------------
	// Static helper methods to compute hash codes.
	// -----------------------------------------------------------------------------------------------

	private static int hash(final int tag, final int value) {
		return 0x7FFFFFFF & (tag + value);
	}

	private static int hash(final int tag, final long value) {
		return 0x7FFFFFFF & (tag + (int) value + (int) (value >>> 32));
	}

	private static int hash(final int tag, final String value) {
		return 0x7FFFFFFF & (tag + value.hashCode());
	}

	private static int hash(final int tag, final String value1, final int value2) {
		return 0x7FFFFFFF & (tag + value1.hashCode() + value2);
	}

	private static int hash(final int tag, final String value1, final String value2) {
		return 0x7FFFFFFF & (tag + value1.hashCode() * value2.hashCode());
	}

	private static int hash(
			final int tag, final String value1, final String value2, final int value3) {
		return 0x7FFFFFFF & (tag + value1.hashCode() * value2.hashCode() * (value3 + 1));
	}

	private static int hash(
			final int tag, final String value1, final String value2, final String value3) {
		return 0x7FFFFFFF & (tag + value1.hashCode() * value2.hashCode() * value3.hashCode());
	}

	private static int hash(
			final int tag,
			final String value1,
			final String value2,
			final String value3,
			final int value4) {
		return 0x7FFFFFFF & (tag + value1.hashCode() * value2.hashCode() * value3.hashCode() * value4);
	}

	/**
	 * An entry of a SymbolTable. This concrete and private subclass of {@link Symbol} adds two fields
	 * which are only used inside SymbolTable, to implement hash sets of symbols (in order to avoid
	 * duplicate symbols). See {@link #entries}.
	 *
	 * @author Eric Bruneton
	 */
	private static class Entry extends Symbol {

		/**
		 * The hash code of this entry.
		 */
		final int hashCode;

		/**
		 * Another entry (and so on recursively) having the same hash code (modulo the size of {@link
		 * #entries}) as this one.
		 */
		Entry next;

		Entry(
				final int index,
				final int tag,
				final String owner,
				final String name,
				final String value,
				final long data,
				final int hashCode) {
			super(index, tag, owner, name, value, data);
			this.hashCode = hashCode;
		}

		Entry(final int index, final int tag, final String value, final int hashCode) {
			super(index, tag, /* owner = */ null, /* name = */ null, value, /* data = */ 0);
			this.hashCode = hashCode;
		}

		Entry(final int index, final int tag, final String value, final long data, final int hashCode) {
			super(index, tag, /* owner = */ null, /* name = */ null, value, data);
			this.hashCode = hashCode;
		}

		Entry(
				final int index, final int tag, final String name, final String value, final int hashCode) {
			super(index, tag, /* owner = */ null, name, value, /* data = */ 0);
			this.hashCode = hashCode;
		}

		Entry(final int index, final int tag, final long data, final int hashCode) {
			super(index, tag, /* owner = */ null, /* name = */ null, /* value = */ null, data);
			this.hashCode = hashCode;
		}
	}
}
